I. Field of the Invention
The present invention relates generally to turbochargers and, more particularly, to a turbocharger with an improved lubrication system.
II. Description of the Prior Art
There have been a number of previously known devices which hydrostatically damp a shaft rotatably mounted to a housing. Examples of such devices are shown in U.S. Pat. No. 3,881,841 to Straniti, May 6, 1975 and U.S. Pat. No. 3,158,413 to Shelley, Nov. 24, 1964.
In these previously known devices, a thin layer of lubricant, commonly known as a squeeze film damper, is entrapped between an outer race of the bearing assembly and the housing in which the shaft is rotatably mounted. This squeeze film damper hydrostatically damps shaft vibration by hydrostatic action.
There have, however, been a number of previously known disadvantages with such hydrostatically damped bearing assemblies. One such disadvantage is that, after a period of time, the lubricant which forms the squeeze film damper deteriorates. Unless new lubricant is supplied to the squeeze film damper, the dampening action of the squeeze film damper will be degraded. The same is also true when the lubricant leaks from the squeeze film damper.